Various processes require temperature monitoring for effective control. Such processes obviously include manufacturing processes, but can also include transportation, security, maintenance, and other types of processes during which monitoring the thermal characteristics of devices is necessary or advisable. Today, increasingly, manufacturing processes are automatically controlled; such processes generally require electronic temperature measurement. Further, microcontrollers and processors--common control means in automatic processes--require digital, as opposed to analog, temperature measurements.
Heretofore, the assignee of the present invention has developed thermal management products--primarily temperature sensors--that provide a direct-to-digital output. Because the sensors made by the assignee of the present invention provide a digital reading of temperature directly, any need for an A/D converter dedicated to temperature measurement is eliminated. Assignee's sensors also do not require inherently analog or external discrete components, such as thermistors, for proper operation. Because of the aforementioned characteristics, assignee's sensors can easily be incorporated into integrated circuits.
Notwithstanding the work mentioned above, direct-to-digital temperature sensors still have a number of shortcomings. First and foremost, the costs of manufacturing are high, primarily because the devices must be calibrated--generally trimmed--multiple times. Trimming, in turn, is essential to obtain even reasonable accuracy. Offset voltages and mismatched currents prevent even reasonable accuracy if not addressed by trimming. In many cases, trimming is extremely expensive because a bath is required, which necessitates prepackaging with non-volatile memory.
In view of all of the foregoing, there is a clear need for a direct-to-digital temperature sensor that has reduced manufacturing costs, but high accuracy.